1. Field of the Invention
The present invention relates to a conveying method and a conveyor apparatus for performing inclined conveyance of articles including vertical conveyance by superposing two belts and pinching and holding the matter to be conveyed between the belts.
2. Description of the Prior Art
Various conveyor apparatuses which are capable of conveying by superposing two belts which are arranged oppositely and which pinch and hold matter to be conveyed between the belts have been developed. Among others, one technique is shown in the specification of Great Britain Patent No. 969429. This patent describes a conveyor apparatus which is capable of performing inclined conveyance including the vertical conveyance of articles composed of a pulverulent body, a granular body, a massive body or fluid and the like.
In another prior art conveyor apparatus, a larger tensile force is given to the longitudinal direction of the belts. A supporting belt and a cover belt are arranged oppositely, and the matter to be conveyed is conveyed by pinching and holding between the said belts by action of the said tensile force.
Also, the said conveyor apparatus is constructed so that a smooth conveying state can be maintained by arranging a curved conveying portion respectively on a shifting portion from a horizontal conveying position to an inclined conveying position including a vertical conveyance and on a shifting portion from the inclined conveying position to a horizontal conveying portion. The matter to be conveyed is conveyed by pinching and holding with a supporting belt and a cover belt in the course of the curved conveying portion from the said curved conveying portion through the inclined conveying portion. Further, the said inclined conveying portion is usually constituted as a linear conveying portion.
In order that the matters to be conveyed which are pinched and held by the belts of two sheets may not drop and leak out from an end of the belt, as shown in the Official Gazette of Japanese Patent Disclosure No. 25078/1979, the conveyor apparatus includes plural guide roller groups arranged in staggered order along the ends of the superposed belts in the inclined conveying portion.
As shown in the Official Gazette of Japanese Patent Disclosure No. 71476/1978, the conveyor apparatus includes plural tightened rollers which are activated in the direction of the belts by springs arranged on both sides of the superposed belts in the inclined conveying portion. This prevents dropping the matter to be conveyed and the matter to be conveyed is raised by the tightened rollers.
In each of the said conveyors, a pinching and holding force against the matter to be conveyed is generated by providing a larger tensile force in comparison with a usual belt conveyor in the longitudinal direction of the superposed belts in order to prevent dropping or leakage of the matter to be conveyed in the inclined conveying portion. The ends of the superposed belts are pressed and attached by staggered guide roller groups so that dropping of the matter to be conveyed may be prevented by pressing the matter to be conveyed by means of tightening rollers from both sides of the superposed belts.
When a large force is applied in the longitudinal direction of the superposed belts and the matter to be conveyed is pinched and held by action of the force, the larger tensile force is given to the whole of the belt, and the said tensile force acts upon the horizontal conveying portion of the belt and the sides of the return wherein a pinching and holding force is not required.
Therefore, it is necessary that the tensile strength of the belt be large and that the rigidity of the belt be high for use in the said conveyor apparatus. Because of this, the cost of the belt will be expensive and the required production time will be greatly increased.
Additionally, when the ends of the superposed belts are pressed and attached by the guide roller groups which are positioned in staggered arrangement, the belts which are superposed by the guide roller groups are curved in a zigzag state. The matter to be conveyed is pinched and held and it is necessary that the tensile force be applied to the longitudinal direction of the belt in order to positively pinch and hold the matter to be conveyed. On account of this, belt fabrication costs and time required for manufacturing will be increased.
When dropping the matter to be conveyed is prevented by tightening rollers from both sides of the superposed belts, the pressure within the superposed belts rises, and there is the possibility that the matter to be conveyed will leak and spurt from the end of the belt.